Where the above-mentioned U.S. Pat. No. 4,547,786 related to an ink jet printing system for printing onto a plurality of flat rigid panels, the present invention relates to an ink jet printing system wherein the printing head is moved laterally of a rotating cylinder such that the material to be printed on is wrapped around the cylinder and the cylinder rotated to provide movement of the printing head relative to the sheet in one direction, and wherein the printing head is provided on a moveable carriage for relative movement between the sheet and the printing head and another coordinate direction. The printing heads comprise a closely spaced array of differently pigmented ink which are adapted to eject relatively large volume drops onto the sheet material to create the desired graphic.